When the crowd in Ammonihah became upset with Alma to the point that they were about to physically attack him, Alma attempted to counter that rage with a rhetorical argument. They had questioned his authority, declaring, "Who is God, that sendeth no more authority than one man among this people" (Alma 9:6) Alma responded:
Behold, O ye wicked and perverse generation, how have ye forgotten the tradition of YOUR fathers; yea, how soon ye have forgotten the commandments of God. Do ye not remember that OUR FATHER, LEHI, was brought out of Jerusalem by the hand of God? Do ye not remember that they were all led by him THROUGH THE WILDERNESS? And have ye forgotten so soon how many times he delivered OUR FATHERS out of the hands of their enemies, and preserved them from being destroyed, even by the hands of their own brethren? (Alma 9:8-10)
Brant Gardner notes that by understanding the cultural background here, the reader can appreciate some of Alma's rhetorical tactics. Many of the people of Ammonihah had Hebrew ancestors, but their language, culture, and their God had become corrupted. They had become Mesoamericanized. They were caught between Old World Traditions and New World philosophies, specifically here the order of Nehor.
By appealing to Lehi, Alma is appealing to what has come to be seen as the legitimate line of rulers--at least for the period prior to the reign of the judges if not thereafter. Thus Alma begins by an appeal to authority--the authority that allowed Mosiah to rule over a people he had almost literally stumbled into.
This appeal to authority is done in a powerful way, for Alma indicates that these are THEIR fathers. Thus Alma is including the Ammonihahites in the tradition, and places them in a position where they should be "Nephites"--politically and religiously. Alma invokes an authority and a tradition that they must recognize, since they are a people that is under the political hegemony that is termed Nephite. [Brant Gardner, "Book of Mormon Commentary," [http://www.highfiber.com/~nahualli/LDStopics/Alma/Alma9.htm], pp. 3-4]
Note* It also should be mentioned that the elements attributed by Alma to the tradition of Lehi ("being brought out of Jerusalem by the hand of God," being "delivered out of the hands of their enemies," and being "led through the wilderness") would also have been part of the Mulekite tradition (compare Omni 1:15-16). These common elements might also have "struck a chord" in the heart of the people of Ammonihah who had Mulekite heritage. [Alan C. Miner, Personal Notes]